The invention relates to a system for transferring a fluid between a first surface installation and a second surface installation floating on an expanse of water, such as a sea or an ocean, for example. This transfer system in particular comprises a tubular conduit whereof one of the ends is connected to the piping of the first surface installation and whereof the other end is designed to be connected to the manifold of a second surface installation. The tubular conduit is supported by a support structure that may be deployed between a storage position on the first surface installation and a position deployed to connect the end of the tubular conduit to the manifold of the second surface installation.
The first surface installation is for example a floating production storage and offloading ship (FPSO).
The second surface installation is for example a floating liquefied hydrocarbon storage and transport ship, in particular for liquefied petroleum gas (LPG), in order to transport it from the floating treatment plant to a land-based site.
In light of the security constraints imposed due to the hazardous nature of the transported fluids and the environment in which those fluid transfers occur, the fluid transfer system must be suitable for bearing major dynamic stresses without any risk of damage to the fluid transfer system.
Known from WO02092422 are systems of this type for transferring liquefied natural gas (LNG) between two installations. This device comprises a cryogenic hose that deploys in a catenary between the two surface installations. One end of the cryogenic hose is connected to the piping of a first installation while the second free end is designed to be connected to a manifold of a second surface installation. The free end of the cryogenic conduit is connected to the first end of a hinged arm that makes it possible to guide the free end of the flexible cryogenic conduit and connect it on the manifold of the second surface installation. This arm is suspended below the stationary support structure by its ends using cables. The first end of the arm on which the flexible cryogenic conduit is connected is linked to the support structure by a cable that can be unwound from a winch located on the stationary support structure while the second end of the arm is linked to the stationary support structure by a cable. It also comprises a counterweight.
The end of the cryogenic conduit is therefore guided to be connected to the manifold of the second surface installation by a hinged arm suspended by its ends from a stationary structure. The suspension of the arm by a cable and a counterweight at the end of the arm ensures a state of stable equilibrium and further makes it possible to reduce the maneuvering forces during the connection to the manifold of the surface installation and the forces thereon, including during the transfer.
However, one drawback of the system is that it is not suitable when the transfer is done between two ships moored to one another and where the heights of the freeboards of the two ships are very different, as is for example the case between an FPSO and a liquefied petroleum gas storage ship during the LPG transfer. In fact, the support structure, and in particular the hinged guide arm, is bulky and is not easily adaptable to the aforementioned configuration. Another drawback of the system is that it does not make it possible to effectively compensate for the primary movements of the boats, mainly heaving. In fact, the hinged arm has considerable movement inertia, which creates significant forces at the manifold requiring the reinforcement thereof.
The fluid transfer system according to the invention is an improvement of the device of the prior art in the applicant's name, and aims to resolve the aforementioned drawbacks.